Twi's no Rarity, but I doubt she would have ever been opposed to bath-time, specially with her favorite foalsitter. Sanitation being important, and all that.

And poor Smarty Pants is being left ooout. Why? Well, Twi wants to do homework afterwards, and Smarty takes hours to dry off properly, so the poor doll only gets washed on weekends... Twilight has it marked down on her calendar, and everything!

Cannot handle the cuteness overload! This almost looks like it's from a newspaper comic strip, with how you did the shading. Neat. Also, I really like how you were able to make Twi's mane look wet from the bath water--I think that's my favorite bit of this, aside from the overall "AWWW" of it.